To prepare for the “Nankai Trough Great Earthquake” which is expected to occur soon, we will develop houses with shelters for evacuation as earthquake countermeasures and tsunami countermeasures. According to the Cabinet Office announcement on Aug. 29, 2012, about 6,400 people are expected to die due to tsunami and about 1,800 people are expected to die due to fire in the Nankai Trough Great Earthquake, in Aichi Prefecture. And 95,000 people are expected to die in neighboring Shizuoka prefecture. Compared with the assumption of the Central Disaster Prevention Council in 2003, the number of deaths announced by the Cabinet Office in 2013 has greatly increased by 13 times. Tsunami would kill 230,000 people, accounting for 70% of the total deaths. The awareness of earthquake and tsunami countermeasures has been increasing in recent years.
Various proposals have been made on a method of fixing a shelter to a foundation as shown in Patent references 1 to 4 and the like.
According to the invention of Patent Reference 1, a sliding door 1 that can withstand impulsive water pressure, a viewing window improved from a pressure resistant manhole, and a manhole 2 for auxiliary evacuation are installed on a wall/roof in a reinforced concrete shelter 6.
According to Patent Reference 2, a seismically isolated structure with a low-rise type building body 1 made of precast pre-stressed concrete as a material and having a general shape of reversed ship bottom is proposed. The foundation portion of the building body 1 is structured by digging down the ground, providing a solid foundation 2 made of reinforced concrete, forming a lattice frame 4a partitioning into an appropriate size on the solid foundation 2 via a plurality of seismic isolation devices 3, providing a base slab 4 filled with filling back earth X in a groove 4b partitioned by the frame 4a, and providing the building body 1 on the base slab 4.
According to Patent Reference 3, an underground shelter fixed to a concrete foundation 2 is proposed. The underground shelter has an escape entrance 6 at the top and and an shelter main body 3 made of nonconcrete material selected from a fiber reinforced plastic, carbon fiber, Kepler fiber, polycarbonate concrete, metal or combination thereof at the bottom, and the escape entrance 6 and the shelter main body 3 are connected by an escape hatch 5 and an escape tube 20.
According to Patent Reference 4, by raising the floor 12 of the evacuation room 3 from the ceiling lowermost portion 15 of the entrance 2 of the tsunami shelter main body 3, the seawater surface 13 invading into the interior at the time of the disaster does not enter the evacuation room 3, and the evacuees 16 are saved by discharge 14 of oxygen cylinders or air cylinders. Since the airtightness of the evacuation room 3 is not influenced by the opening and closing of the entrance door 8, there is no need to close the door 8 at the time of evacuation, and the entrance 2 is not blocked at the time of escape. Inventions have been proposed which have a function to withstand a collision 18 such as pressure of a tsunami and rubble washed by the tsunami by tilting the outer wall and providing sufficient self-weight of the tsunami shelter 1 itself and fixation to the ground 5.